The objective of this proposal is to bring to completion the only large- scale data-based longitudinal investigation of the pathognomonic development of childhood stuttering with special reference to differentiating two subgroups: those exhibiting persistent, chronic stuttering, and those exhibiting spontaneous remission. The specific aims are to test the hypotheses that (a) persistent and recovered stuttering reflect different genetic liabilities; (b) persistent stuttering is linked to deficits or differences in other development areas, including motor speech, language, phonologic, and cognitive capacities, and (c) the two subgroups can be differentiated at an early stage. Analysis of longitudinal data on the formative stages of stuttering will respond to several important needs. First, data concerning the genetic basis, as well as other epidemiologic aspects, will provide a solid foundation for theoretical models of the disorder. Second, subgrouping of stuttering will greatly improve precision of all research in the area. Third, the data will facilitate early diagnosis of stuttering and will allow prediction of High-Risk, Low-Risk, and No- Risk for chronic stuttering. Fourth, it will provide a scientific basis for timing of clinical intervention, as well as for differential treatment at each stage. The ongoing longitudinal study of more than 150 stuttering children, extending from onset through a period of 6 years, will be completed. Multiple characteristics of the subjects and their families will be observed, tested, and/or recorded periodically. The rate, magnitude, and timing of remission and persistency will be determined. Data from familial pedigrees,medical and developmental records, analyses of stuttering from audio and video recordings, acoustic analyses of temporal speech features, tests of phonologic, linguistic and motoric skills, nonverbal cognitive functions, and other areas, will be used to compare persistent with recovered subjects and with 50 control subjects. By applying various statistical methods to data obtained from subjects at frequent intervals, it will be possible to discern subgroups that emerge along diverging developmental trends and determine factors governing them. By progressively retracing group data to early testing sessions, it will be possible to identify criteria for early estimates for remission or for a chronic disorder. Comparisons of pedigree data against genetic models will test the inheritance factor.